Who should we be testing?

Lauren Vogel | CMAJ | March 27, 2020

Aggressive testing and contact tracing were key to South Korea and Taiwan’s response, but it’s unclear if that’s still being done in Canada.

This week saw rising tensions over delays in testing and rationing of personal protective equipment in Canada, and an exponential increase in new cases. To put these developments in perspective, CMAJ reached out to infectious disease specialists Dr. Srinivas Murthy of BC Children’s Hospital and the University of British Columbia in Vancouver, Dr. Matthew Oughton of Jewish General Hospital and McGill University in Montreal, and Dr. Alon Vaisman of the University Health Network in Toronto.

CMAJ: What developments in Canada’s outbreak concerned you most this week and what were most promising?

Vaisman: Cases continue to rise, seemingly following some predictions showing a rapid surge that’s going to happen sometime in mid-April. If you look at hospitals in Ontario, some have already started to see significant numbers of patients with COVID-19, but most are not at 100% capacity yet.

Murthy: Things have kicked into another gear with community spread being more prevalent and arguably the main route of person-to-person transmission [in BC]. Our intensive care units are coping… but strain exists at the level of diagnostic testing and at the level of materials.

Oughton: Most concerning are ongoing reports of difficulties in the supply chain of personal protective equipment (PPE) for health care workers. The war against SARS-CoV-2 is being fought on the front lines of healthcare facilities across this country and the healthcare workers who are our soldiers need the security of knowing they will have a reliable supply of high-quality PPE. Most encouraging is the announcement that Canadian centres will soon start enrolling patients in clinical research trials… If PPE is the armor for our healthcare workers, then properly evaluated treatments and vaccines are the weapons that will help us win the war.

CMAJ: Aggressive testing and contact tracing were key to flattening the curve of outbreaks in South Korea and Taiwan, yet some have started to question if that’s still being done in Canada. How do our efforts compare?

Murthy: I wouldn’t say we’re at the level of those East Asian countries… Should we be doing more tests to rule out disease? Yes.

Oughton: Provinces across Canada have been steadily ramping up their capacity to perform diagnostic assay for SARS-CoV-2, but these efforts must continue as the numbers of new cases continue to rise. Although testing is necessary, it is not sufficient; the data from testing needs to be analyzed rapidly and used by local public health authorities to identify disease clusters and intervene in order to prevent further transmission.

Vaisman: Across the country it’s going to be variable. Some municipalities are going to be well funded and have lots of staff. Some will be simply overwhelmed with the number of cases. So, it’s hard to know how well we’re doing… Social distancing is what happens when you simply don’t know. If we knew exactly who in our population had the virus, then we would not need social distancing, we would just strictly enforce quarantine for infected individuals.

CMAJ: If shortages of testing resources weren’t an issue, whom should we be testing?

Oughton: In an ideal world with no limitation on assay reagents, I would want us to test as many contacts of cases of possible. This would enable us to more quickly define conditions that promote and inhibit disease transmission, which would in turn enhance the effectiveness of our public health and infection prevention measures.

Murthy: In a perfect world we would swab every single person in Canada and isolate people as soon as they became positive and then the outbreak would be over, but that’s impossible to do. People who are symptomatic and at higher risk of disease and health care workers should be tested.

Vaisman: For those individuals who are not at high risk or say a health worker, if you have mild symptoms it’s irrelevant whether you’re positive or negative, you should just treat yourself as positive, stay home and isolate.

CMAJ: The World Health Organization warned that the US is set to become the next epicenter of the pandemic. What will that mean for Canada?

Oughton: Given how interconnected Canada and the United States are, this will inevitably have major ramifications for Canada. I expect that trade between these countries will be significantly reduced overall. I also wonder if we will begin to see “medical refugees” who will want to leave particularly hard-hit areas of the United States in order to find more stability and better access to health care… possibly here in Canada.

Murthy: Having more cases in the United States puts Canada at higher risk, without a doubt. There is only so much that borders can do, and we put a lot of reliance on imaginary lines to protect us, when in fact, people will cross those borders. We need to make sure we have good public health strategies to contain as much as possible people who are symptomatic… If we can keep those policies strong, then we should be okay.

Vaisman: If Canada gets on top of this sooner than the US, which it probably will, given that our population is smaller and more dispersed, and that we were better prepared it seems, how can we move forward when our neighbor hasn’t?

CMAJ: Cases in Quebec escalated rapidly this week. What do you make of that spike?

Vaisman: There are a lot of variables that could factor into that spike… It could be because they have more testing, or it could be because they have more access to health care, or it could be because their criteria for testing are different… The simple reason might be you have more people infected with the virus.

Oughton: Increased numbers of tests are partially responsible, as was the shift from “Persons under investigation” to “Confirmed cases” that occurred once the province stopped requiring all positive [tests] to be confirmed at the provincial reference laboratory. There is a very early suggestion that mitigation measures may be having some effect on disease prevalence, as the numbers of new confirmed cases per day have not been increasing since Mar. 24, but this is very preliminary and I would not extrapolate too far until we see consistent trends for several more days.

CMAJ: There’s growing concern that hospitals will soon run out of protective equipment. How will the outbreak change if we run out?

Oughton: Running out of proper PPE would be catastrophic to our healthcare system on several levels. At the very least, it would shake the confidence that healthcare workers need to have in their safety when fulfilling their duties to their patients… It is greatly demoralizing when healthcare workers see colleagues contract diseases while on the job, and this would increase rates of burnout and absenteeism at a time when we need our front lines more than ever.

Murthy: The whole purposes of all these social isolation strategies is to protect the healthcare system. In the absence of an ability to protect ourselves, the whole thing falls apart. That being said, health workers need to know what PPE is appropriate in what circumstances… Some institutions have said that wearing a face mask is recommended for all staff, and that’s not necessarily based on any science or any known transmission dynamics of the virus.

Vaisman: Federal and provincial governments should treat this as nothing short of an emergency… Imagine the improvement in the anxiety of frontline staff if we don’t have to talk about PPE again. The only way that’s going to happen is if we have a sustainable supply from inside the country. Such a rich country, with so many resources, it seems insane to me that we can’t supply ourselves.